Boiler furnace



Dec., 24, 1935. J. e. COUTANT BOILER FURNACE Original Filed Jan. 31,1927 2 Sheets-Sheet l i\ ero/307 Ja o a& Cm

I ooo /////0 u M v C Dec., 24, 1935( J. G. COUTANT BOILER FURNAGEOriginal Filed Jan.- 31, 1927 2 Sheets-Sheet 2 ,in/venia:

WWMW mwa Patented Dec. 24, 1935 JNITED' STATES &025342 PATENT OFFICEOriginal application January 31, 1927, Serial No. 164324. Divided andthis application May 18,

1933, Serial No. 6711584 4 Ciaims.

This invention is a novel boiler furnace, and is applicable to varioustypes of furnace, but is more especially useful in boiler furnaces suchas employed in large power houses or central Stations, whereinpulverized coal in suspension in air is supplied to the furnace, eitherdirectly from a pulverizer or from storage and where the highestCapacity and heat efciency are important.

An object of the present invention is to combine with means forintroducing or injecting fuel into a combustion chamber, with or Withoutreintroduced mineral or fly ash', a. cooled bottom or floor, adaptedtoreceive and support the heavier particles of uel and the greater partof the injected fly ash settling through the combustion chamber, and 'todelay their progress: toward the ash discharge or final exit, sothat'they may be thoroughly burned out by the radiant heat, in

the presence of additonal air admitted preferably through the floor,before going to waste; and it is found that with a correctly designedfurnace the extent of unburned carbon in the ash pit refuse may be keptto a very low percentage or practically negligible; this incidentallyincreasing the value of the ash pit refuse as a by-product.

The invention also saves labor, since a substantially less weight of ashis required to be removed from the iurnace, and this is all taken fromthe ash diecharge opening or pit, which in turn permits the use of anyautomatic ash removing systhus substantially eliminating labor cost inthe removal of refuse. Moreover, ashes completely burned out andsubstantially free from carbon have a marketable value for variouspurposes, fire and building materials, cinder concrete, ground fill andthe like.

Other aid further objects and advantages of the present invention willbe explained in'the hereinafter following description of specificembodiments thereof.

?in the accompanying drawings Figure 1 is a genoral eideelevation of theinterior of a boiler furnace enhodying the present invention, thefurnace walls and baies shown in section.

Fig. 2 is a top plan view of the floor or bottomof the conibustionchamber shown in Fig. 1.

Fig. 3 is a longitudinal section'taken on the line 3--3 of Fig. 2.

Fig. l is a transverse section taken on the line -ti of Fig. 2.

Fig. 5 interier elevational View looking toward the f rt of the furnace,that is toward the right in showing the front wall and the arrangementof admission means for the fuel and ash.

Figs. 6 and 7 are transverse sections, corresponding with' Fig. 4, butshowing two difierent modications of the floor structure, also availablefor the arch.

Fig. 8 is a transverse section showing an embodiment of the invention ina different type of furnace.

Fig. 9 is a section on the line 9-9 of Fig. 8.

This application is a division of my application Serial No. 164,824,filed January 31, 1927.

The illustrated furnace is shown as having a front wall t, a rear walli@ and side walls I'I enclosing the combustion chamber i& The chamber isalso closed at the upper rear portion by an arch !5 and below thecharnber is a cooled bottom or floor Zt beneath which'and above theconcrete foundation is an air box or space 2! through which preheatedair may be supplied through the floor as will be described. The floor isinclined downwardly toward the front and at this point the front wall isprovided with an ash opening closed by a door 22 by which ashes andother matter may be removed by hand, although the discharge and removalof ash could likewise be effected mechanically or otherwise. Ashessitting through the floor 2& into the space 2! may similarly be removedthrough a door 22 by hand or otherwise.

The furnace and combuston chamber may be of practically any known typeor design and the same is true of the boiler and its relation to thecombustion chamber. A boiler of the Stirling type is illustrativelyshown, this co mprisng a lower or water drum 23 and a plurality of upperor steam drums 24 together with a first bank of boiler tubes 25extend'ng from the lower to an upper drum and. subsequent banks ofboiler tubes 26,'21 and 28. Between the first and second banks of boilertubes is shown a baffie or wall 3I over which the gaseous products ofcombustion must travel. Between the second and third banks of tubes is abafiie wall 32 below which the products travel and between the third andfourth banks o'f tubes is a third bafe wall 33 above which the bulk ofthe products of combustion travel, although, for reasons to bedescribed, I have provided a small gap or aperture 3@ between the loweredge of the b aifle 33 and the drum 23 through which accumulating dustand ashes may pass by short cut to the ash chamber to' be described.With this arrangement of boiler tubes and baffies the boiler may besaid. to` comprise a plurality of passes; the first boiler pass 36consisting of the space or passage between the rear wall !6 and thebaffie 3l, the second boiler pass 31 being the guished from other typesof flame.

space between the bafiies 3! and 32, the third pass 38 being the spacebetween the bafiles 32 and 33 and the fourth pass 39 being the spacebetween the third baflle 33 and the boiler front wall er extension 40 ofthe furnace structure. The gaseous products of combustion thereforetravel upwardly through the first pass 35, downwardly through the secondpass, upwardly through the third pass, except for a small portion of theproducts which travel directly through the aperture 34, and downwardlythrough the final pass 39; the products thence passing through the exit4! to'the Stack or preliminarily to an economizer or dust collector orother auxiliary apparatus. The lower end of the boiler wall 43 is shownconnected by a horizontalwall 42 with the main front wall |5 so as toenclose an ash chamber 43 of ample prcportions, this chamber receiving alarge portion of the fly ash, diverted from the downward stream in thefourth boiler pass, and received through the opening 34 at the lower endof the third baffle 33. The space 43 therefore constitutes an ashpocket, receptacle, or space, adapted to receive the fly ash for thepurposes of the present invention, and this chamber may be taken asillustrativeof the principles involved, which may be extended also tothe fly ash received in dust collectors or in the flue's, stack orelsewhere.

When pulverized fuel is used it may be supplied to the furnace byinjection and the front wall !5 is shown as formed'with a fuel entranceor aperture 45, into which aperture extends a burner 45 which may be anyone of many well known types of burner, preferably a burner containingmeans for giving a whirling motion to the fuel Suspended in air driveninto the furnace, so as to produce a short flame and immediatecombustion as distin- The burner may be supplied direct from apulverizing machine through a pipe 48. The'burner 45 is shown as havinga spreader 41 at its delivery end to accentuate the spreading action ofthe gases, producing a flame indicated roughly at 49. The flame is notforcible but is intensely hot, and beyond the flame body the gasestravel upwardly toward the boiler and thence through the respectiveboiler passes as already described. The air of combustion is largely orwholly supplied in or adjacent to the burner. 'It will be observed thatthe burner is spaced slightly from the walls of the fuel entrance 45, sothat supplemental air is drawn in by induction to take part in thecombustion. Supplemental air may be introduced at the opposite or rearWall or at the other points in the furnace, for example through thebottom or floor to be described.

According to this invention the'flyash recovered from the outgoing gasesis to be reintroduced into the combustion chamber. This may be done 'invarious ways, but in my preferred form the fly ash is introduced at apoint adjacent to or slightly higher than the flame 49 and in a mannerto be well distributed or spread across the furnace and to sprinkle orrain downwardly through'the hot gases, taking part in the combustionreactions, and eventually being disposed of, partly by being carried outWith the combustion gases and partly by precipitating upon the floor orbottom and being removed through the ash door, pit or other ash removalmeans. For purposes of illustration the ash chamber 43 is shown aspartly filled up With fly ash 5 I.

The front wall !5 of the combustion chamber is formed with a series ofthrough apertures 52 constituting an ash entrance into the combustionchamber. While various modes may be employed for drivng the fine locseash into the chamber there is shown, as an illustrative method, a steampipe 53 in each of the ash entrance apertures 52, so that by driving afine jet of steam through the entrance, a current is induced and drawsthe fine ash from'the ehamber 13 and throws it forcibly toward themiddle of the combustion chamber. The several steam nozzles 53 are shownconnected to a common steam pipe or header 54 which eX- tendstransversely through the ash chamber and may be provided with acontrclling valve 55 outside the furnace so that the jets can be thrownout of operation when desired. The ash recirculating system hereof bedesired to be thrown out of action at certain times and for this purposethere is shown a sliding door or damper 53 in the nature of a metalplate formed with apertures 57 corresponding with the ash entranceapertures 52. Fig. 5 shows the apertures 52 and 5? in alinement so thatthe system is in condition for recirculation of ash. The damper or slide55, guided in metallic guides or strips 58 may extend to an externalpoint so that by sliding it lengthwise the several ash entrance openingsmay be closed.

A Wide distribution or rain of ashis indicated generally at 59; someparticles may pass up- Wardly With the products of combustion, asindicated, whereas the bulk of the recirculated ash may descend andprecipitate toward the floor, forming a thin layer 69. The arrangementis preferably such that the ashes precipitating on the floor have agradual trend or movement toward the ash door 22, where the ashes willaccumulate as indicated at SI unless and until removed by hand orotherwise. The preferred details of the floor will be next described.

The floor or bottom of the combustion chamber of this invention ispreferably cooled in a suitable manner. For this purpose a system ofwater tubes 63 may be provided, forming part of the floor. These tubesare preferably inclined, for example their front ends may be lower than'their rear ends. A front header 64 is shown connected by a pipe 65 withthe lower or water drum of the boiler, so that the floor tubes are indirect circulation with the boiler, and receive water from the lowerdrum through the downtake 65. The upper or rear ends of the floor tubesare' similarly interconnected by a rear header 66 from which theascending hot water or steam passes by a connecting pipe or uptake (STto a top rear header 53 from which a series or system of short boiler'tubes 63 are shown extended, along the under.

side of the arch !9, and directly exposed to the flames of combustion,to the rearmost of the upper boiler drums 24.

Referring next to the floor Construction this is preferably a cooledfloor, as stated, for example water cooled, and is also preferablyconstructed with slits, gaps or other apertures so as to permit theupward percolation of air from the air box Zi through the floor andthrough the thin layer of fine ash overlying the floor, thus supplyingthe necessary air for the final and complete combustion of the carbonremaining in the ash, and at the same time having the efect to lift orfloat the ash to a certain extent and keep it in mo'tion so that underthe influence of gravity it Will travel progressively or graduallytoward the ash door. An illustrative form of such a floor is shown inFig. 1 and in detail in Figs. 2, 3 and 4. A system of iron or other highconducting blocls 'll is shown. resting upon the Water tubes 63 andpreferably shaped to the tubes so as to rapidly conduct to the tubes andcirculating water the radiant and other heat received from thecombustion space. An extensive infiow of air is not desired and there isshown a system of longitudinal ribs 12 at the edges of the blocksengaging with corresponding grooves 13 at the opposite edges, so thatthe blocks are held in horizontal alinement, but spaced slightly apartso as to leave slits or gaps 'M through which air can percolate upwardlyas described, the rib and groove structure being such as to restrictwithout totaly obstructing the upflow of' air. In a longitudinaldirection the floor blocks 'H may be spaced from each other by means ofsmall buttons or projections 15 at their ends, thus producing narrowgaps or slits 'Hi in a crosswise direction. The upward percolation ofair is thus distributed thoroughly over the entire area of the floor. Inorder that the character of the air passage through the slits 16 maycorrespond with that through the slits 'M the side edges of the blocksare shown formed respectively with overlying and underlying shoulders Tiand 'ia which engage in a manner to restrict, but not to totallyobstruct the upflow of air.

The air up-fiowing through the cooled floor does not require to be ofatmospheric temperature and maybe preheated. A preheating passage 8@ isshown in the rear wall IB of the urnace, controlled by a series ofdampers Bl regulating the amount of air passing into the passage andthereby the rate of air inflow through the percolating floor. Anaperture 82 is shown in the rear wall at'a point above the floor toadmit air at that point if desirable, under control of a damper. Thepreheating passage however is carried to the base of the furnace andthere connects with an entrance or passage 33 to the air box 2! beneaththe furnace floor or bottom, thus providing preheated air as stated. Thefloor is thus cooled both by the air drawn through its crevices orperforations and by the water circulation tubes, and is in that wayprotected from over-heating and from slagging of molten ash. The air hasbeen preheated and will be further preheated in filtering through thefloor. This air conduces to quick and thorough combustion of residuecarbon as it is of high oxygen content.

Among the various modiflcations which are possible there are showncertain modifications in the construction of the floor. For example inmg. 6 the water tubes 63 are shown as Contacting directly against thefoundation 65 so as to form narrow air spaces 2 I The iron floor blocks'i l are similar to the blocks 'H already described excepting that inFig. 6 they do not extend as far down, but preferably only to thediameter of the water tubes. With this form there is a decided saving infurnace space, and therefore first cost and the floor is equallyeffective inasmuch as the underneath passages ZI are ample to Convey thenecessary air to all parts of the floor. In Fig. 7 a variation is shownwherein the floor blocks 'i l dier from the blocks 'H in that theyentirely surround the water tubes 63 and may be slipped upon the tubesand shrunlr into place, leaving slight gaps or slits' 'M as before. Theblocks ?i should have high conducting power and are preferably composedof steel or cast iron. In the case of some of the forms the floor blockscould be made of silicon carbide.

It has been stated that the present invention is applicabie to varioustypes of furnace and boiler and Figs. 8 and shown an embodiment appliedto a furnace of the type having a so-called hopper bottom, with oppositeinclined sides converging toward a common or central ash pit ordischarge. Fig. 8 shows one of the furnace walls 92 and at the bottomthe two opposite floor sections 93, each of which embodies steameirculation tubes 94 connected by lower headers 95 and upper headers 96,with an ash pit 91 between and below the two floor sections, and an ashremoval gate 98 at the bottom of the pit. In the wall 92, above thefurnace bottom, is shown an ash entrance or aperture me for introducingash into the combustion chamber. A pipe e conveys fly ash by gravity tothe aperture te@ and at the point of introduction there is shown anozzle !02 which may be operated by air, steam, or other fluid to drawand. inject the ashes into the furnace. It will be understood that inthis and other modiflcations the ashes can be brought to the deliverypoint in any desired manner such as a screw conveyor. In the enibodimentshown in Fig. 8 the ashes are introduced at a point relatively lowerthan in Fig. 1. To a lesser degree than in Fig. 1 the ashes will takepart in the combustion process, the ashes forming a stream or shower mewhich precipitates toward the floor or bottom, passing along the floorby gravity toward the ash pit while subject to final and completecornbustion through the exposure to radiant heat in the presence ofadditional air of combustion introduced through the floor as alreadydescribed. Fig. 9 shows a convenient form of floor structure for thispurpose, the floor composed of separate metaliic blocks !04 overlyingthe tubes 94 and clamped thereto by clamping devices !05 which preventaccidental displacement of blocks in the case of steeply slanted floors.The blocks :se are shown to be spaced slightly apart forming airpercolation slits which permit the air to find its way between the blockand the tube due to the naturally rough character of the surface of thecast block; air also being admitted through slits between longitudinallyadjacent blocks as in the other embodiments. Below the described floorstructure are air passages me permitting air to have access to all partsof the water floor.

With the type of furnace shown in Figs. 8 and 9 the fly ash or injectedmineral matter may Conveniently be introduced through one or moreinjecting devices in each of the two opposite side walls, so that thematerial is distributed and sprinkled into the combustion space fromopposite directions. In this embodiment or in the embodiment shown inthe main figures of the drawings the fly ash or other mineral insuspension may be introduced along with the inj ected fuel, for examplethrough the burne r. An embodiment of this is indicated in Fig. 1wherein a iphon tube 52 is extended directly into the Iuel supply pipeas, the siphon connected with the sh chamber 43, and the forciblytraveling stream of fuel and air Operating by suction to draw the ashesdown from the chamber, so that the fuel and air have the ashes mixedwith them upon injection into the* combustion chamber. In the pipeconnecting the ash chamber with the fuel pipe is shown a slide valve 62which may be closed or opened more or less to regulate the ash siphoningaction. The slide valve is shown closed, whereas the other described ashinjecting means are shown in operation. The arrangement can be reversedby mere adjustment, or for that matter the ashes may be introducedsimultaneously by both methods.

The use of cooled floor having its surface broken heat in the presenceof the additional air in-.

filtering or percolating upwardly through the crevices of the floor. Ifthe floor openings are 'not too large there will be no appreciabledownward sifting of ashes, but on the contrary the upflow of air throughevery aperture has a lifting, tumbling or agitating effect, supportingthe fine particles, promoting their combustion, and assisting theirgradual travel toward the final discharge. For example, in the case of afloor divided by'longitudinal and lateral' crevices as illustrated ithas been found that a thin layer of soft ash will accumulate on eachsmall section or island of the floor, for example six by seven inches insize, each small layer or pile glowing red at its top surface, and thesmall partieles of fuel and ash, in constant motion, progressing fromisland to island toward the ash door or pit,

' constantly subject to ideal conditions for consuming the remainingcarbon. The floor structure can be varied extensively, and may be builtup of perforated blocks through which air ascends tages of the presentinvention. Since many matr ters of Construction, arrangement,combination and operation may be variously modified without departingfrom the principles it is not intended to limit the invention to suchmatters except so far as set forth in the appended claims.

What is claimed is:

l. A boiler furnace wherein the boiler surface is contiguous to thecombustion chamberand wherein is means to inject pulverized fuel andprimary air into such chamber for radiant combustion of such fueltherein in suspension in air, and wherein below thecombustion chamber isan air chamber supplying additional air for combustion; said furnacecomprising an inclined slag-preventing cooled bottom to the combustionchamber separating it from the air chamber and adapted to support alayer of refuse material under eXposure to the radiant heat above, saidbottom having a system of spaced-apart inclined Water tubes incirculation with the boiler, and overlying and protecting such tubes asystem of material-supporting blocks providing a bottom structure havingan extensive system of crevices permitting upward'percolation of additional combustion 'air from the air I chamber through the bottom andthrough such layer of mat rial thereon into the combustion chambercrevices into the air chamber against such air upfiow, whereby suchmaterial mainly is conned above the bottom and trends progressively tothe lowest part of the combustion chamber,

and the combustion chamber having an ash discharge exit near its lowestpart for removal of ash from abovethe bottom without entering the airchamber.

2. A boiler furnace wherein the boiler surface is contiguous to thecombustion chamber and wherein is means to inject pulverized fuel andprimary air into such chamber for radiant combustion of such fueltherein in suspension in air, and wherein below the combustion chamberis an air chamber supplying additional air for combustion; said furnacecomprising an inclined cooled bottom to the combustion chamberseparating it from the air chamber and adapted to support a layer ofcombustible-containing material under exposure to the radiant heatabove,

said bottom having a system of spaced-apart inclined water tubes incirculation with the boiler,

and between such tubes an extensive system of i crevices permittingupward percolation 'of additional combustion air from the air chamberthrough the bottom and through such layer of material thereon into thecombustion chamber but such crevices being so narrow that the bottom issubstantially closed against extensive sift-' ing of such materialdownwardly through the crevices into the air chamber against such airupfiow, whereby such material mainly is confined' above the bottom andtrends progressively to the lowest part of the combustion chamber, andthe combustion chamber having an ash discharge exit near its lowest partfor removal of ash from above the bottom without entering the airchamber. 3. A boiler furnace wherein the boiler surface is contiguous tothe combustion chamber and wherein is means to inject pulverized fueland primary air into such chamber for radiant combustion of such fueltherein in suspension in air. and wherein below the combustion chamberis an air chamber supplying additional air for com bustion; said furnacecomprising an inclined bottom to the combustion chamber separating itfrom the air chamber and adapted to support a layer ofcombustible-containing material under exposure to the radiant heatabove, said bottom having a system of spaced-apart inclined water tubesin circulation with the boiler and an extensive system of crevicespermitting upward percolation of additional combustion air from the airchamber through the bottom and through such layer of material thereoninto the combustion chamber but such crevices being so narrow that thebottom is substantially'closed against extensive sifting of suchmaterial downwardly through the crevices into the air chamber againstsuch air upflow; such furnace having a separate means for thesupplemental introduction and distribution in the combustion chamber ofwaste material containing combustible to be received and burned upon thefloor, and the combustion chamber having an ash discharge exit near itslowest part for removal of ash from above the floor without entering theair chamber.

4. A boiler furnace wherein the boiler surface is contiguous to thecombustion chamber and wherein is means to inject pulverized fuel andprimary air into such chamber for radiant combustion of such fueltherein in suspension in air, and wherein below the combustion chamberis an air chamber supplying additional air for combustion; said furnacecomprising an inclined cooled bottom to the combustion chamberseparating it from the air chamber and adapted to support a layer ofcombustible-containing material under exposure to the radiant heatabove, said bottom having a system of spaoed-apart circulation tubes orpassages for cooling fluid, and between such tubes an extensive systemof crevices permitting upward percolation of additional combustion airfrom the air chamber through the bottom and through such layer ofmaterial thereon into the combustion chamber but such crevces being sonarrow that the bot- 10 tom is substantially closed against extensivesfting of such material downwardly through the crevces into the airchamber against such air upfiow, whereby such material mainly isconfined above the bottom and. trends progressively to the lowest partof the combustion chamber, and the combustion chamber having an ashdischarge exit near its lowest part for removal of ash from above thebottom without entering the air chamber.

JAY GOULD COUTANT.

